2009 Ford Flex drivetrain & axles problems

My flex started having a hard jerk and bang when going from reverse to park. Was not always but frequent. The car started to run hot when sitting in a drive thru or traffic but would go right back down when I started moving. I took it into s mechanic and he replaced the fan. After replacing the fan the car began to have a really bad grinding noise when idling or traveling. Do bad I did not want to drive it. I took it into the ford dealership and after 2 days they call and say they can't find anything wrong.

Transmission. When the temperature is 40 degrees or below I sometimes have an automatic transmission problem. In the morning after the vehicle was parked over night I start the vehicle, put it into reverse, I back 40 feet down my driveway which has about a 30 degree grade down to the street.. I stop on the street, put it into drive and turn to the right to proceed forward up the street with about 10 degree grade for about 300 feet, then the street has about a 15 degree grade for the next 200 feet after which it…